Heat exchangers and air conditioning systems

Abstract

The purpose of this disclosure is to provide a heat exchanger and an air conditioning system that suppress the occurrence of uneven flow in heat transfer tubes. [Solution] The outdoor heat exchanger comprises a plurality of flattened tubes and a cylindrical liquid header. The liquid header has refrigerant flow paths formed inside, connected to the plurality of flattened tubes. The refrigerant flow paths have an upward space 34z and a downward space. The upward space 34z extends from the inlet 34e into which the refrigerant flows in, along the longitudinal direction of the liquid header, toward the upper end of the liquid header. The downward space has a supply flow path 35z that communicates with the end of the upward space 34z opposite to the inlet 34e, and extends from the supply flow path 35z along the longitudinal direction of the liquid header toward the lower end of the liquid header. The cross-sectional area of ​​the flow path at a first position P1 of the upward space 34z is different from the cross-sectional area of ​​the flow path at a second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header.

Description

Technical Field

[0001] Relates to a heat exchanger and an air conditioner.

Background Art

[0002] A heat exchanger having a cylindrical header to which a plurality of heat transfer tubes are connected is known.

[0003] Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-125748) discloses a heat exchanger including a header (header header pipe) in which one ends of a plurality of heat transfer tubes (flat tubes) are connected and extending along the vertical direction.

[0004] The header included in the heat exchanger of Patent Document 1 has a partition member that divides the internal space into a first space on the side where the heat transfer tubes are connected and a second space where the heat transfer tubes are not connected. In the partition member, two communication passages that communicate the first space and the second space are formed at positions separated by a predetermined distance in the longitudinal direction of the header. As a result, a loop structure is formed inside the header, and the refrigerant flowing into the header flows from one end side to the other end side in the first space and then flows from the other end side to the one end side in the second space. As a result, the mixing of the liquid-phase refrigerant and the gas-phase refrigerant flowing through the header is promoted.

[0005] In addition, the header included in the heat exchanger of Patent Document 1 is provided with a nozzle that generates an upward flow in the first space when the heat exchanger functions as an evaporator. Thereby, the flow velocity of the refrigerant flowing into the first space from the inlet is increased, and sufficient supply of the refrigerant to the heat transfer tubes connected to the position away from the inlet is achieved.

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] However, even with such a header, when the dryness of the flowing refrigerant is high, an imbalance in the pressure distribution occurs inside, and a bias flow may occur in which there is a bias in the distribution of the liquid-phase refrigerant and the gas-phase refrigerant in the plurality of connected heat transfer tubes.

[0007] The purpose of this disclosure is to provide a heat exchanger and an air conditioning system that suppress the occurrence of flow deviation in heat transfer tubes. [Means for solving the problem]

[0008] The heat exchanger relating to the first aspect is a heat exchanger comprising a plurality of heat transfer tubes and a cylindrical header. The header has refrigerant flow paths formed inside that are connected to the plurality of heat transfer tubes. The refrigerant flow paths are The entry space, the nozzle, and the inlet, A first channel, a first communication port, and a second channel , the second connecting passage and It holds. The nozzle's length in the second direction, which is perpendicular to the longitudinal direction of the heat transfer tube when viewed from the first direction, which is the longitudinal direction of the header, is shorter than the length of the introduction space in the second direction, allowing refrigerant that has passed through the introduction space to flow in. The inlet is connected to one end of the nozzle, allowing refrigerant that has passed through the nozzle to flow in. The first flow path extends from the inlet through which the refrigerant flows in, along the first direction which is the longitudinal direction of the header, to the first end of the header. The first communication port communicates with the end of the first flow path opposite to the inlet. The second flow path communicates with the first communication port and extends from the first communication port along the first direction to the second end of the header. The second communication port connects to the first channel at the end of the second channel opposite to the first communication port.

[0009] Multiple heat transfer tubes are connected to a first flow path so as to intersect in a first direction. The first flow path has a different cross-sectional area at a first position and a second position located at a predetermined distance from the first position toward the first end of the header.

[0010] According to this heat exchanger, by making the flow path area at the first position of the first flow path different from the flow path cross-sectional area at the second position, the first flow path can be shaped in a way that suppresses pressure distribution imbalance. Therefore, according to this heat exchanger, the occurrence of flow deviation in the heat transfer tube is suppressed.

[0011] The heat exchanger relating to the second perspective is the heat exchanger relating to the first perspective, wherein the first position is near the inlet.

[0012] A heat exchanger relating to the third aspect is a heat exchanger relating to the first or second aspect. , flow The refrigerant that flows into the first flow path from the inlet flows into the second flow path from the first communication port, and then flows into the first flow path through the second communication port.

[0013] This heat exchanger uses a first flow path, a first communication port, a second flow path, and a second communication port to create a loop for the refrigerant, thereby eliminating the pressure distribution imbalance in the first flow path.

[0014] The heat exchanger relating to the fourth viewpoint is any of the heat exchangers relating to the first viewpoint to the third viewpoint, wherein the flow path cross-sectional area increases from the first position to the second position.

[0015] This heat exchanger facilitates the upward movement of the refrigerant flowing in from the inlet to the first flow path, thereby eliminating the pressure distribution imbalance in the first flow path.

[0016] The heat exchanger relating to the fifth aspect is the heat exchanger relating to the fourth aspect, wherein the second position is located in the center in the first direction. The flow path cross-sectional area decreases as you move from the second position toward the first end of the header.

[0017] This heat exchanger facilitates the movement of the refrigerant flowing in from the inlet to the center of the first flow path, thereby eliminating the imbalance in the pressure distribution in the first flow path.

[0018] A heat exchanger relating to the sixth aspect is a heat exchanger relating to the fourth or fifth aspect, wherein the shape of the cross-sectional area of ​​the first flow path changes in a direction perpendicular to the longitudinal direction of the heat transfer tube as viewed from the extending direction of the first flow path, as it moves from the first position toward the first end of the header.

[0019] The heat exchanger relating to the seventh viewpoint is any of the heat exchangers relating to the fourth viewpoint to the sixth viewpoint, wherein the shape of the cross-sectional view of the first flow path changes in the longitudinal direction of the heat transfer tube as viewed from the extending direction of the first flow path, as the flow path cross-section of the first flow path moves from the first position toward the first end of the header.

[0020] A heat exchanger relating to the eighth viewpoint is any of the heat exchangers relating to the first viewpoint to the seventh viewpoint, wherein the longitudinal direction of the header coincides with the vertical direction.

[0021] The air conditioner according to the ninth aspect includes a refrigerant circuit including any one of the heat exchangers according to the first to eighth aspects, and executes an operation in which the dryness of the refrigerant at the inlet of the heat exchanger is 0.25 or more.

[0022] The air conditioner according to the tenth aspect includes a refrigerant circuit including any one of the heat exchangers according to the first to eighth aspects, and the refrigerant circuit is filled with a single refrigerant composed of any one of propane, CO2, and isobutane, or a mixed refrigerant including any one of propane, CO2, and isobutane.

[0023] In a refrigerant circuit filled with natural refrigerants such as propane, CO2, and isobutane, the dryness at the inlet of the heat exchanger becomes high, and uneven flow is likely to occur in the heat transfer tubes. However, according to the air conditioner provided with the above-described heat exchanger, even when using natural refrigerants such as propane, CO2, and isobutane, the occurrence of uneven flow in the heat transfer tubes is suppressed.

[0024] The heat exchanger relating to the 11th aspect is a heat exchanger relating to the first aspect, wherein the header is provided with multiple spaces connecting the heat transfer tubes and the first flow path between the heat transfer tubes and the first flow path. The multiple spaces are arranged along the longitudinal direction of the header.

[0025] The heat exchanger relating to the twelfth aspect is the heat exchanger relating to the first aspect, wherein the first flow path has a flow path cross-sectional area at a first position that is smaller than the flow path cross-sectional area at a second position.

[0026] A heat exchanger relating to the 13th aspect is a heat exchanger relating to the first aspect, wherein the first flow path has a flow path cross-sectional area at a first position that is larger than the flow path cross-sectional area at a second position.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic configuration diagram of the air conditioner 1. [Figure 2] [[ID=##]] It is a schematic perspective view of the outdoor heat exchanger 11. [Figure 3] It is a partially enlarged view of the heat exchange part 27 of the outdoor heat exchanger 11. [Figure 4] It is a schematic view showing the attachment state of the fin 29 to the flat tube 28 in the heat exchange part 27. [Figure 5] It is an explanatory view showing the state of the refrigerant flow in the outdoor heat exchanger 11 that functions as an evaporator of the refrigerant. [Figure 6] It is a side view external appearance configuration diagram showing a state in which the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 300. It should be noted that in the original text, there seems to be a duplicate tag ID "32" with the same content " ". I have translated it as is. If this is an error in the original, it may need to be corrected in the source material. [Figure 7] This is an exploded perspective view of the area near the upper end of the liquid header 30. [Figure 8] This is a cross-sectional view of the liquid header 30 in plan view. [Figure 9] This is a plan view cross-sectional view showing how the branched liquid refrigerant connection pipes 49a to 49e and the flat pipe 28 are connected to the liquid header 30. [Figure 10] This is a cross-sectional perspective view of the portion near the upper end of the liquid header 30. [Figure 11] This is a schematic diagram of the first liquid-side member 31 as seen from the rear. [Figure 12] This is a schematic diagram of the second liquid-side member 32 as seen from the rear. [Figure 13] This is a schematic diagram of the third liquid-side member 33 as seen from the rear. [Figure 14] This is a schematic diagram of the fourth liquid-side member 34 as seen from the rear. [Figure 15] This is a schematic diagram of the fifth liquid-side member 35 as seen from the rear. [Figure 16] This is a schematic diagram of the sixth liquid-side member 36 as seen from the rear. [Figure 17] This is a schematic diagram of the seventh liquid-side member 37 as seen from the rear. [Figure 18] This is a cross-sectional view from the right side of the area around the rising space 34z of the outdoor heat exchanger 11 according to modified example 1A. [Figure 19] This is an exploded perspective view of the portion near the upper end of the liquid header 30 of the outdoor heat exchanger according to the second embodiment. [Figure 20] This is a schematic diagram showing the fourth liquid-side member 38 of the liquid header 30 of the outdoor heat exchanger according to the second embodiment, viewed from the rear. [Figure 21] This is a cross-sectional view from the right side of the area around the rising space 34z1 of the outdoor heat exchanger according to modified example 2A. [Modes for carrying out the invention]

[0028] <First Embodiment> (1) Configuration of the air conditioning system An air conditioning system 1 equipped with a heat exchanger according to the first embodiment of this disclosure will be described with reference to the drawings.

[0029] Figure 1 is a schematic diagram of the air conditioning system 1.

[0030] The air conditioning system 1 is a device that performs cooling and heating operations in a space to be air-conditioned by performing a vapor compression type refrigeration cycle. The space to be air-conditioned is, for example, a space inside a building such as an office building, commercial facility, or residence. Note that the air conditioning system is merely one example of a refrigerant cycle device, and the heat exchanger in this disclosure may also be used in other refrigerant cycle devices, such as refrigerators, freezers, water heaters, floor heating systems, etc.

[0031] As shown in Figure 1, the air conditioning system 1 mainly comprises an outdoor unit 2, an indoor unit 9, a liquid refrigerant connecting pipe 4 and a gas refrigerant connecting pipe 5, and a control unit 3 that controls the equipment constituting the outdoor unit 2 and the indoor unit 9. The liquid refrigerant connecting pipe 4 and the gas refrigerant connecting pipe 5 are refrigerant connecting pipes that connect the outdoor unit 2 and the indoor unit 9. In the air conditioning system 1, the refrigerant circuit 6 is formed by connecting the outdoor unit 2 and the indoor unit 9 via the liquid refrigerant connecting pipe 4 and the gas refrigerant connecting pipe 5.

[0032] The refrigerant supplied to the refrigerant circuit 6 is a well-known refrigerant such as HFC refrigerant, HFO refrigerant, or natural refrigerant. As will be described in detail later, natural refrigerants such as propane, CO2, and isobutane, which tend to have a high degree of dryness, are also suitable for cooling. These natural refrigerants may be used as a single refrigerant or as a mixture of refrigerants.

[0033] In Figure 1, the air conditioning system 1 has one indoor unit 9, but the air conditioning system 1 may have multiple indoor units 9 connected in parallel to each other to the outdoor unit 2 by liquid refrigerant connecting pipes 4 and gas refrigerant connecting pipes 5. The air conditioning system 1 may also have multiple outdoor units 2. Furthermore, the air conditioning system 1 may be an integrated type air conditioning system in which the outdoor unit 2 and the indoor unit 9 are formed as a single unit.

[0034] (1-1) Outdoor unit The outdoor unit 2 is installed outside the space to be air-conditioned, for example, on the roof of a building or near the wall of a building.

[0035] The outdoor unit 2 mainly comprises an accumulator 7, a compressor 8, a four-way switching valve 10, an outdoor heat exchanger 11 (an example of a heat exchanger), an expansion mechanism 12, a liquid-side shut-off valve 13 and a gas-side shut-off valve 14, and an outdoor fan 16.

[0036] The outdoor unit 2 mainly has an intake pipe 17, a discharge pipe 18, a first gas refrigerant pipe 19, a liquid refrigerant pipe 20, and a second gas refrigerant pipe 21 as refrigerant pipes that connect various devices constituting the refrigerant circuit 6. The intake pipe 17 connects the four-way switching valve 10 to the intake side of the compressor 8. An accumulator 7 is provided in the intake pipe 17. The discharge pipe 18 connects the discharge side of the compressor 8 to the four-way switching valve 10. The first gas refrigerant pipe 19 connects the four-way switching valve 10 to the gas side of the outdoor heat exchanger 11. The liquid refrigerant pipe 20 connects the liquid side of the outdoor heat exchanger 11 to the liquid side shut-off valve 13. An expansion mechanism 12 is provided in the liquid refrigerant pipe 20. The second gas refrigerant pipe 21 connects the four-way switching valve 10 to the gas side shut-off valve 14.

[0037] The compressor 8 is a device that draws in low-pressure refrigerant from the refrigeration cycle through the suction pipe 17, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed refrigerant to the discharge pipe 18.

[0038] The four-way switching valve 10 is a mechanism that changes the state of the refrigerant circuit 6 between cooling operation and heating operation by switching the direction of refrigerant flow. When the refrigerant circuit 6 is in cooling operation, the outdoor heat exchanger 11 functions as a refrigerant radiator (condenser), and the indoor heat exchanger 91 functions as a refrigerant evaporator. When the refrigerant circuit 6 is in heating operation, the outdoor heat exchanger 11 functions as a refrigerant evaporator, and the indoor heat exchanger 91 functions as a refrigerant condenser. When the four-way switching valve 10 sets the state of the refrigerant circuit 6 to cooling operation, the four-way switching valve 10 connects the suction pipe 17 to the second gas refrigerant pipe 21 and the discharge pipe 18 to the first gas refrigerant pipe 19 (see the solid line in the four-way switching valve 10 in Figure 1). When the four-way switching valve 10 sets the refrigerant circuit 6 to the heating operation state, the four-way switching valve 10 connects the suction pipe 17 to the first gas refrigerant pipe 19 and the discharge pipe 18 to the second gas refrigerant pipe 21 (see the dashed line inside the four-way switching valve 10 in Figure 1).

[0039] The outdoor heat exchanger 11 (an example of a heat exchanger) is a device that performs heat exchange between the refrigerant flowing inside and the air (heat source air) at the installation location of the outdoor unit 2. Details of the outdoor heat exchanger 11 will be described later.

[0040] The expansion mechanism 12 is located in the refrigerant circuit 6 between the outdoor heat exchanger 11 and the indoor heat exchanger 91. In this embodiment, the expansion mechanism 12 is located in the liquid refrigerant pipe 20 between the outdoor heat exchanger 11 and the liquid side shut-off valve 13. In this air conditioning system 1, the expansion mechanism 12 is located in the outdoor unit 2, but it may be located in the indoor unit 9, which will be described later. The expansion mechanism 12 is a mechanism that adjusts the pressure and flow rate of the refrigerant flowing through the liquid refrigerant pipe 20. In this embodiment, the expansion mechanism 12 is an electronically controlled expansion valve with a variable opening, but the expansion mechanism 12 may also be a temperature-sensitive tube type expansion valve or a capillary tube.

[0041] The accumulator 7 is a container with a gas-liquid separation function that separates the incoming refrigerant into gaseous refrigerant and liquid refrigerant. Furthermore, the accumulator 7 is a container with a storage function for excess refrigerant generated in response to fluctuations in operating load, etc.

[0042] The liquid-side shut-off valve 13 is a valve located at the connection point between the liquid refrigerant pipe 20 and the liquid refrigerant connecting pipe 4. The gas-side shut-off valve 14 is a valve located at the connection point between the second gas refrigerant pipe 21 and the gas refrigerant connecting pipe 5. The liquid-side shut-off valve 13 and the gas-side shut-off valve 14 are open when the air conditioning system 1 is in operation.

[0043] The outdoor fan 16 is a fan that draws in external heat source air into the casing of the outdoor unit 2 (not shown) and supplies it to the outdoor heat exchanger 11, and discharges the air that has exchanged heat with the refrigerant in the outdoor heat exchanger 11 to the outside of the casing of the outdoor unit 2. The outdoor fan 16 is, for example, a propeller fan.

[0044] (1-2) Indoor Unit The indoor unit 9 is a unit installed in the space to be air-conditioned. The indoor unit 9 is, for example, a ceiling-mounted unit, but it may also be a ceiling-suspended, wall-mounted, or floor-standing unit. The indoor unit 9 may also be installed outside the space to be air-conditioned. For example, the indoor unit 9 may be installed in an attic, machine room, garage, etc. In this case, an air passage is installed to supply air that has exchanged heat with the refrigerant in the indoor heat exchanger 91 from the indoor unit 9 to the space to be air-conditioned. The air passage is, for example, a duct.

[0045] The indoor unit 9 mainly consists of an indoor heat exchanger 91 and an indoor fan 92.

[0046] In the indoor heat exchanger 91, heat exchange takes place between the refrigerant flowing through the indoor heat exchanger 91 and the air in the space to be air-conditioned. The indoor heat exchanger 91 is not limited to a specific type, but for example, it is a fin-and-tube type heat exchanger having multiple heat transfer tubes (not shown) and fins. One end of the indoor heat exchanger 91 is connected to the liquid refrigerant connecting pipe 4 via refrigerant piping. The other end of the indoor heat exchanger 91 is connected to the gas refrigerant connecting pipe 5 via refrigerant piping.

[0047] The indoor fan 92 is a mechanism that draws air from the space to be air-conditioned into the casing (not shown) of the indoor unit 9, supplies it to the indoor heat exchanger 91, and blows the air that has exchanged heat with the refrigerant in the indoor heat exchanger 91 back into the space to be air-conditioned. The indoor fan 92 is, for example, a turbo fan. However, the type of indoor fan 92 is not limited to a turbo fan and can be selected as appropriate.

[0048] (1-3) Control Unit The control unit 3 is a functional unit that controls the operation of various devices that make up the air conditioning system 1.

[0049] The control unit 3 is configured such that, for example, the outdoor control unit (not shown) of the outdoor unit 2 and the indoor control unit (not shown) of the indoor unit 9 are communicated to each other via a transmission line (not shown). The outdoor control unit and the indoor control unit are units that have, for example, a microcomputer and a memory that stores various programs for controlling the air conditioning system 1 that the microcomputer can implement. For convenience, in Figure 1, the control unit 3 is drawn in a location separate from the outdoor unit 2 and the indoor unit 9.

[0050] Furthermore, the functions of the control unit 3 do not necessarily need to be realized through the cooperation of the outdoor control unit and the indoor control unit. For example, the functions of the control unit 3 may be realized by either the outdoor control unit or the indoor control unit, or a control device (not shown) different from the outdoor control unit and the indoor control unit may realize some or all of the functions of the control unit 3.

[0051] As shown in Figure 1, the control unit 3 is electrically connected to various components of the outdoor unit 2 and indoor unit 9, including the compressor 8, four-way switching valve 10, expansion mechanism 12, outdoor fan 16, and indoor fan 92. The control unit 3 is also electrically connected to various sensors (not shown) provided in the outdoor unit 2 and indoor unit 9. Furthermore, the control unit 3 is configured to communicate with a remote control (not shown) operated by the user of the air conditioning system 1.

[0052] The control unit 3 controls the operation and stopping of the air conditioning system 1, as well as the operation of the various components that make up the air conditioning system 1, based on measurement signals from various sensors and commands received from a remote control (not shown).

[0053] (2) Configuration of the outdoor heat exchanger The configuration of the outdoor heat exchanger 11 will be explained with reference to the drawings.

[0054] Figure 2 is a schematic perspective view of the outdoor heat exchanger 11. Figure 3 is a magnified view of the heat exchange section 27 of the outdoor heat exchanger 11, which will be described later. Figure 4 is a schematic diagram showing the mounting state of the fins 29, which will be described later, to the flat pipe 28 in the heat exchange section 27. Figure 5 is an explanatory diagram showing the flow of refrigerant in the outdoor heat exchanger 11, which functions as a refrigerant evaporator. The arrows in the heat exchange section 27 shown in Figure 5 indicate the flow of refrigerant during heating operation (when the outdoor heat exchanger 11 functions as an evaporator).

[0055] In the following explanation, expressions such as "up," "down," "left," "right," "front," and "back" may be used to describe orientation and position. Unless otherwise specified, these expressions follow the direction of the arrows drawn in Figure 2. These expressions for orientation and position are used for the convenience of explanation and, unless otherwise specified, do not specify the orientation or position of the entire outdoor heat exchanger 11 or the individual components of the outdoor heat exchanger 11 to be the orientation or position of the expressions described.

[0056] The outdoor heat exchanger 11 is a device that performs heat exchange between the refrigerant flowing inside and the air.

[0057] The outdoor heat exchanger 11 mainly comprises a flow divider 22, a group of flat tubes 28G including a plurality of flat tubes 28, a plurality of fins 29, a liquid header 30 (an example of a header), and a gas header 70. In this embodiment, the flow divider 22, flat tubes 28, fins 29, liquid header 30, and gas header 70 are all made of aluminum or an aluminum alloy.

[0058] As will be described later, the flattened tubes 28 and the fins 29 fixed to the flattened tubes 28 form a heat exchange section 27. The outdoor heat exchanger 11 has a single row of heat exchange sections 27, and does not have multiple flattened tubes 28 arranged in the direction of airflow. In the outdoor heat exchanger 11, heat exchange takes place between the refrigerant flowing through the flattened tubes 28 and the air flowing through the ventilation passage formed by the flattened tubes 28 and fins 29 of the heat exchange section 27. The heat exchange section 27 is divided into a first heat exchange section 27a, a second heat exchange section 27b, a third heat exchange section 27c, a fourth heat exchange section 27d, and a fifth heat exchange section 27e, which are arranged in the vertical direction.

[0059] (2-1) Flow divider The flow divider 22 is a mechanism for dividing the refrigerant. It also serves as a mechanism for merging the refrigerants. The liquid refrigerant pipe 20 is connected to the flow divider 22. The flow divider 22 has multiple diversion pipes 22a to 22e. The flow divider 22 has the function of dividing the refrigerant flowing from the liquid refrigerant pipe 20 into the multiple diversion pipes 22a to 22e and guiding it to multiple spaces formed within the liquid header 30. Furthermore, the flow divider 22 has the function of merging the refrigerant flowing from the liquid header 30 via the diversion pipes 22a to 22e and guiding it back to the liquid refrigerant pipe 20. Specifically, each of the diversion pipes 22a to 22e and the multiple spaces within the liquid header 30 are connected via branch liquid refrigerant connection pipes 49a to 49e, respectively.

[0060] (2-2) Squamous tube group The flat tube group 28G is an example of a heat transfer tube group. The flat tube group 28G includes multiple flat tubes 28 as multiple heat transfer tubes. The flat tube 28 is a flat heat transfer tube having flattened surfaces 28a on the top and bottom, which serve as heat transfer surfaces, as shown in Figure 3. Multiple refrigerant passages 28b through which the refrigerant flows are formed in the flat tube 28, as shown in Figure 3. For example, the flat tube 28 is a flat multi-hole tube with many refrigerant passages 28b having small cross-sectional areas through which the refrigerant flows. In this embodiment, these multiple refrigerant passages 28b are arranged in the direction of airflow. The maximum width of the flat tube 28 in a cross-section perpendicular to the refrigerant passages 28b may be 70% or more of the outer diameter of the main gas refrigerant pipe connection portion 19a, or it may be 85% or more.

[0061] In the outdoor heat exchanger 11, as shown in Figure 5, multiple flattened pipes 28 extending horizontally between the liquid header 30 and the gas header 70 are arranged in a series of vertical rows. As a result, the multiple flattened pipes 28 are connected to the upward space 34z, which will be described later, so as to intersect (orthogonal in the case of the outdoor heat exchanger 11) the longitudinal direction of the liquid header 30. In this embodiment, the flattened pipes 28 extending between the liquid header 30 and the gas header 70 are bent at two points, and the heat exchange section 27 composed of the flattened pipes 28 is formed in a roughly U-shape in plan view. In this embodiment, the multiple flattened pipes 28 are arranged vertically at regular intervals.

[0062] (2-3) Finn The multiple fins 29 are components that increase the heat transfer area of ​​the outdoor heat exchanger 11. Each fin 29 is a plate-shaped component that extends in the direction of the rows of flattened pipes 28. The outdoor heat exchanger 11 is used in a configuration in which multiple horizontally extending flattened pipes 28 are arranged in a vertical direction. Therefore, when the outdoor heat exchanger 11 is installed in the outdoor unit 2, each fin 29 extends in the vertical direction.

[0063] Each fin 29 has multiple notches 29a formed in it, as shown in Figure 4, that extend along the insertion direction of the flattened pipes 28, allowing multiple flattened pipes 28 to be inserted. The notches 29a extend in a direction perpendicular to the direction in which the fin 29 extends and the thickness direction of the fin 29. When the outdoor heat exchanger 11 is installed in the outdoor unit 2, the notches 29a formed in each fin 29 extend in the horizontal direction. The shape of the notches 29a in the fin 29 is approximately the same as the outer shape of the cross-section of the flattened pipe 28. The notches 29a are formed in the fin 29 at intervals corresponding to the arrangement spacing of the flattened pipes 28. In the outdoor heat exchanger 11, the multiple fins 29 are arranged in a line along the direction in which the flattened pipes 28 extend. By inserting a flattened tube 28 into each of the multiple notches 29a of the multiple fins 29, the space between adjacent flattened tubes 28 is divided into multiple air passages through which air flows.

[0064] Each fin 29 has a connecting portion 29b that communicates vertically with respect to the flattened pipe 28, either upstream or downstream in the airflow direction. In this embodiment, the connecting portion 29b of the fin 29 is located on the windward side of the flattened pipe 28.

[0065] (2-4) Gas headers and liquid headers The gas header 70 and the liquid header 30 are cylindrical members with refrigerant flow paths formed inside.

[0066] As shown in Figure 5, the liquid header 30 is connected to one end of each flattened pipe 28, and the gas header 70 is connected to the other end of each flattened pipe 28. The outdoor heat exchanger 11 is arranged in a casing (not shown) of the outdoor unit 2 such that the longitudinal directions of the liquid header 30 and the gas header 70 are roughly aligned with the vertical direction (an example of the first direction). In this embodiment, the heat exchange section 27 of the outdoor heat exchanger 11 is formed in a U-shape in plan view, as shown in Figure 2. The liquid header 30 is located near the left front corner of the casing (not shown) of the outdoor unit 2. The gas header 70 is located near the right front corner of the casing (not shown) of the outdoor unit 2.

[0067] (2-4-1) Gas Header The gas header 70 is connected to the main gas refrigerant pipe connection portion 19a and the branch gas refrigerant pipe connection portion 19b, which constitute the end of the first gas refrigerant pipe 19 on the gas header 70 side. Although not particularly limited, the outer diameter of the main gas refrigerant pipe connection portion 19a may be, for example, three times or more, or five times or more, the outer diameter of the branch gas refrigerant pipe connection portion 19b.

[0068] One end of the main gas refrigerant pipe connection portion 19a is connected to the gas header 70 at an intermediate position in the height direction of the gas header 70, so as to communicate with the gas-side internal space 25, which is the refrigerant flow path of the gas header 70.

[0069] One end of the branched gas refrigerant pipe connection 19b is connected to the gas header 70 so as to communicate with the gas-side internal space 25 near the lower end of the gas header 70 in the height direction. The other end of the branched gas refrigerant pipe connection 19b is connected to the main gas refrigerant pipe connection 19a. The branched gas refrigerant pipe connection 19b has a smaller inner diameter than the main gas refrigerant pipe connection 19a and is connected to the gas header 70 below the main gas refrigerant pipe connection 19a. This makes it possible to draw the refrigerant oil accumulated near the lower end of the gas header 70 into the main gas refrigerant pipe connection 19a and return it to the compressor 8.

[0070] (2-4-2) Liquid Header The liquid-side internal space 23 of the liquid header 30 is divided into multiple sub-spaces 23a to 23e, which are refrigerant flow paths of the liquid header 30.

[0071] These multiple sub-spaces 23a to 23e are arranged in the vertical direction. Each sub-space 23a to 23e is not connected to the liquid-side internal space 23 of the liquid header 30.

[0072] Each sub-space 23a to 23e is connected one-to-one with each branch liquid refrigerant connection pipe 49a to 49e, which is connected to each branch pipe 22a to 22e of the shunting device 22. As a result, in cooling operation, the refrigerant that reaches each sub-space 23a to 23e flows through each branch liquid refrigerant connection pipe 49a to 49e and each branch pipe 22a to 22e and merges in the shunting device 22. In heating operation, the refrigerant that has been diverted in the shunting device 22 flows through each branch pipe 22a to 22e and each branch liquid refrigerant connection pipe 49a to 49e and is supplied to each sub-space 23a to 23e.

[0073] (3) Refrigerant flow in the outdoor heat exchanger When the air conditioning system 1 performs heating operation and the outdoor heat exchanger 11 functions as a refrigerant evaporator, the gas-liquid two-phase refrigerant that has reached the diverter 22 from the liquid refrigerant pipe 20 flows through diverter pipes 22a to 22e into the sub-spaces 23a to 23e that constitute the liquid-side internal space 23 of the liquid header 30. Specifically, the refrigerant that flows through diverter pipe 22a flows into sub-space 23a, the refrigerant that flows through diverter pipe 22b flows into sub-space 23b, the refrigerant that flows through diverter pipe 22c flows into sub-space 23c, the refrigerant that flows through diverter pipe 22d flows into sub-space 23d, and the refrigerant that flows through diverter pipe 22e flows into sub-space 23e. The refrigerant that has flowed into the sub-spaces 23a to 23e of the liquid-side internal space 23 flows through the flat pipes 28 connected to each of the sub-spaces 23a to 23e. The refrigerant flowing through each flattened tube 28 evaporates through heat exchange with the air, becoming a gaseous refrigerant that flows into the gas-side internal space 25 of the gas header 70, where it merges with the air.

[0074] When the air conditioning unit 1 is performing cooling or defrosting operations, the refrigerant flows through the refrigerant circuit 6 in the opposite direction to that during heating operations. Specifically, high-temperature gaseous refrigerant flows into the gas-side internal space 25 of the gas header 70 via the main gas refrigerant pipe connection 19a and the branch gas refrigerant pipe connection 19b of the first gas refrigerant pipe 19. The refrigerant that has flowed into the gas-side internal space 25 of the gas header 70 is divided and flows into each flat pipe 28. The refrigerant that has flowed into each flat pipe 28 passes through each flat pipe 28 and flows into the sub-spaces 23a to 23e of the liquid-side internal space 23 of the liquid header 30. The refrigerant that has flowed into the sub-spaces 23a to 23e of the liquid-side internal space 23 merges at the flow divider 22 and flows out into the liquid refrigerant pipe 20.

[0075] (4) Details of the liquid header Figure 6 is a side view showing the connection of branch liquid refrigerant connecting pipes 49a to 49e to the liquid header 30. Figure 7 is an exploded perspective view of the area near the top of the liquid header 30 (the dashed arrows in the figure indicate the refrigerant flow when the outdoor heat exchanger 11 functions as a refrigerant evaporator). Figure 8 is a plan view cross-sectional view of the liquid header 30. Figure 9 is a plan view cross-sectional view showing the connection of branch liquid refrigerant connecting pipes 49a to 49e and the flat pipe 28 to the liquid header 30. Figure 10 is a cross-sectional perspective view of the area near the top of the liquid header 30.

[0076] The liquid header 30 is configured such that, in plan view, its outer shape is approximately rectangular, with the connection point of the flattened pipe 28 as one of its sides. The liquid header 30 includes a first liquid-side member 31, a second liquid-side member 32, a third liquid-side member 33, a fourth liquid-side member 34, a fifth liquid-side member 35, a sixth liquid-side member 36, and a seventh liquid-side member 37. The liquid header 30 is constructed by joining the first liquid-side member 31, the second liquid-side member 32, the third liquid-side member 33, the fourth liquid-side member 34, the fifth liquid-side member 35, the sixth liquid-side member 36, and the seventh liquid-side member 37 to each other by brazing.

[0077] Figure 11 is a schematic diagram of the first liquid-side member 31 viewed from the rear. Figure 12 is a schematic diagram of the second liquid-side member 32 viewed from the rear. Figure 13 is a schematic diagram of the third liquid-side member 33 viewed from the rear. Figure 14 is a schematic diagram of the fourth liquid-side member 34 viewed from the rear. Figure 15 is a schematic diagram of the fifth liquid-side member 35 viewed from the rear. Figure 16 is a schematic diagram of the sixth liquid-side member 36 viewed from the rear. Figure 17 is a schematic diagram of the seventh liquid-side member 37 viewed from the rear. Note that in each of these figures, the positional relationship of the openings of adjacent members is shown by dashed lines, etc., projected onto the diagram.

[0078] It is preferable that the first liquid-side member 31, the third liquid-side member 33, the fourth liquid-side member 34, the fifth liquid-side member 35, the sixth liquid-side member 36, and the seventh liquid-side member 37 are all made of plate material with a thickness of 3 mm or less.

[0079] (4-1) First liquid side member The first liquid-side member 31 is a member that, together with the seventh liquid-side member 37 (described later), forms the periphery of the outer shape of the liquid header 30. Preferably, the first liquid-side member 31 has a cladding layer having a brazing material formed on its surface.

[0080] The first liquid-side member 31 includes a liquid-side flattened pipe connecting plate 31a, a first liquid-side outer wall 31b, a second liquid-side outer wall 31c, a first liquid-side claw portion 31d, and a second liquid-side claw portion 31e.

[0081] Although not particularly limited, the first liquid-side member 31 in this embodiment can be formed by bending a single sheet metal obtained by rolling, with the longitudinal direction of the liquid header 30 (an example of a first direction) as the fold. In this case, the thickness of each part of the first liquid-side member 31 is uniform.

[0082] The liquid-side flat pipe connecting plate 31a is a flat plate-shaped portion that extends in the vertical and horizontal directions. Multiple liquid-side flat pipe connecting openings 31x are formed in the liquid-side flat pipe connecting plate 31a, arranged in a vertical direction. Each liquid-side flat pipe connecting opening 31x is an opening that penetrates the liquid-side flat pipe connecting plate 31a in the thickness direction. The flat pipe 28 is inserted into this liquid-side flat pipe connecting opening 31x so that one end of the flat pipe 28 passes through completely, and the flat pipe 28 is joined by brazing. In the brazed state, the entire inner surface of the liquid-side flat pipe connecting opening 31x and the entire outer surface of the flat pipe 28 are in contact with each other. Here, since the thickness of the first liquid-side member 31, including the liquid-side flat pipe connecting plate 31a, is formed to be relatively thin, for example, 1.0 mm to 2.0 mm, the length of the inner surface of the gas-side flat pipe connecting opening 71x in the thickness direction can be shortened. Therefore, in the preliminary stage before joining by brazing, when inserting the flattened tube 28 into the liquid-side flattened tube connection opening 31x, it is possible to minimize the friction between the inner surface of the liquid-side flattened tube connection opening 31x and the outer surface of the flattened tube 28, thereby facilitating the insertion work.

[0083] The first liquid-side outer wall 31b is a planar portion that extends forward from the front surface of the left end of the liquid-side flat pipe connecting plate 31a (outside the outdoor unit 2, opposite to the gas header 70).

[0084] The second liquid-side outer wall 31c is a planar portion that extends forward from the front surface of the right end (inside the outdoor unit 2, on the gas header 70 side) of the liquid-side flat pipe connecting plate 31a.

[0085] The first liquid-side claw portion 31d is the portion that extends to the right from the front end of the first liquid-side outer wall 31b. The second liquid-side claw portion 31e is the portion that extends to the left from the front end of the second liquid-side outer wall 31c.

[0086] In a plan view, before the second liquid-side member 32, third liquid-side member 33, fourth liquid-side member 34, fifth liquid-side member 35, sixth liquid-side member 36, and seventh liquid-side member 37 are positioned inside the first liquid-side member 31, the first liquid-side claw portion 31d and the second liquid-side claw portion 31e extend along the extensions of the first liquid-side outer wall 31b and the second liquid-side outer wall 31c, respectively. With the second liquid-side member 32, third liquid-side member 33, fourth liquid-side member 34, fifth liquid-side member 35, sixth liquid-side member 36, and seventh liquid-side member 37 positioned inside the first liquid-side member 31 in a plan view, the first liquid-side claw portion 31d and the second liquid-side claw portion 31e are bent closer together, causing the second liquid-side member 32, third liquid-side member 33, fourth liquid-side member 34, fifth liquid-side member 35, sixth liquid-side member 36, and seventh liquid-side member 37 to be crimped and fixed together by the first liquid-side member 31. In this state, brazing is performed in a furnace or the like to join the members together and completely fix them in place.

[0087] (4-2) Second liquid side member The second liquid-side member 32 has a plate-shaped base portion 32a and a plurality of protrusions 32b that project from the base portion 32a toward the liquid-side flat pipe connecting plate 31a. The second liquid-side member 32 does not necessarily have a cladding layer having a brazing material formed on its surface.

[0088] The base portion 32a extends parallel to the liquid-side flat pipe connecting plate 31a and has a plate-like shape with the direction in which the flat pipe 28 extends being the plate thickness direction. The width of the base portion 32a in the left-right direction is the same as the width of the liquid-side flat pipe connecting plate 31a in the left-right direction, excluding the ends. The base portion 32a has a plurality of communication holes 32x formed in the vertical direction, arranged in a one-to-one correspondence with the flat pipe 28, except where the protrusions 32b are provided. When viewed from the rear, the communication holes 32x have a shape that roughly overlaps with the ends of the flat pipe 28.

[0089] The protrusions 32b extend horizontally from between adjacent communication holes 32x on the base portion 32a toward the rear until they strike the front surface of the liquid-side flat pipe connecting plate 31a. This forms an insertion space 32s enclosed by the front surface of the liquid-side flat pipe connecting plate 31a of the first liquid-side member 31, the first liquid-side outer wall 31b and the second liquid-side outer wall 31c of the first liquid-side member 31, the vertically adjacent protrusions 32b on the second liquid-side member 32, and the portion of the rear surface of the base portion 32a of the second liquid-side member 32 other than the communication holes 32x. Multiple insertion spaces 32s are provided in a row along the longitudinal direction of the liquid header 30. The ends of the flat pipes 28 are located in the insertion spaces 32s. Furthermore, the length of the protrusion 32b in the front-to-back direction is adjusted to be longer than the thickness of any of the first liquid-side members 31, 3rd liquid-side member 33, 4th liquid-side member 34, 5th liquid-side member 35, 6th liquid-side member 36, and 7th liquid-side member 37 that constitute the liquid header 30. As a result, even if there is an error in the degree to which the flattened pipe 28 is inserted into the liquid header 30, as long as it is within the range of the length of the protrusion 32b in the front-to-back direction, problems such as blockages or areas where the refrigerant is difficult to flow in the completed liquid header 30 are less likely to occur. In addition, it is possible to suppress the movement of the brazing material due to capillary action during brazing and block the refrigerant passage 28b of the flattened pipe 28.

[0090] (4-3) Third liquid side member The third liquid-side member 33 is a laminated member that is in contact with the front surface of the base portion 32a of the second liquid-side member 32 (the side where the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30). The left-right length of this third liquid-side member 33 is the same as the left-right length of the second liquid-side member 32. Preferably, the third liquid-side member 33 has a cladding layer having a brazing material formed on its surface.

[0091] The third liquid-side member 33 has a third internal plate 33a and a plurality of flow-diverting openings 33x.

[0092] The third internal plate 33a has a flat plate shape that extends in the vertical and horizontal directions.

[0093] Multiple diversion openings 33x are arranged in a vertical direction and are openings that penetrate the third internal plate 33a in the thickness direction. In this embodiment, each diversion opening 33x is formed near the center of the third internal plate 33a in the left-right direction. Furthermore, when viewed from the rear, each diversion opening 33x overlaps with each communication hole 32x of the second liquid-side member 32 and communicates with each other. This allows the refrigerant flowing through the rising space 34z, described later, to be branched and flowed toward each diversion opening 33x, and the refrigerant to be diverted to each flat pipe 28 connected to correspond to each diversion opening 33x.

[0094] Furthermore, the front surface of the third internal plate 33a, excluding the portion where the flow diversion opening 33x is formed, forms the outline of the upward space 34z, which will be described later.

[0095] (4-4) Fourth liquid side member The fourth liquid-side member 34 is a laminated member that is in contact with the front surface of the third internal plate 33a of the third liquid-side member 33 (the side where the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30). The length of the fourth liquid-side member 34 is the same as the length of the third liquid-side member 33. The fourth liquid-side member 34 does not necessarily have a cladding layer having a brazing material formed on its surface.

[0096] The fourth liquid-side member 34 has a fourth internal plate 34a and a first through-portion 34o.

[0097] The fourth internal plate 34a has a flat plate shape that extends in the vertical and horizontal directions.

[0098] The first through-portion 34o is an opening formed in the fourth internal plate 34a so as to penetrate in the thickness direction, and has an introduction space 34x, a nozzle 34y, and an upward space 34z (an example of a first flow path). In this embodiment, the introduction space 34x, the nozzle 34y, and the upward space 34z are arranged vertically from bottom to top. In this embodiment, the widths of the introduction space 34x, the nozzle 34y, and the upward space 34z are the same in the front-to-back direction.

[0099] The introduction space 34x, the nozzle 34y, and the upward space 34z are spaces sandwiched in the front-rear direction between the front surface of the third internal plate 33a of the third liquid-side member 33 and the rear surface of the fifth internal plate 35a of the fifth liquid-side member 35, which will be described later.

[0100] The introduction space 34x faces the wall portion 33aa of the third internal plate 33a of the third liquid-side member 33, and does not overlap with the flow diversion opening 33x when viewed from the rear, nor does it communicate with the flow diversion opening 33x. However, when viewed from the rear, the introduction space 34x overlaps with the second communication opening 35x of the fifth liquid-side member 35, which will be described later, and communicates with the second communication opening 35x. Thus, since the rear side of the introduction space 34x is covered by the wall portion 33aa of the third internal plate 33a, the gaseous refrigerant flowing into the introduction space 34x and the liquid refrigerant mix upon contact with the wall portion 33aa, and are then sent to the rising space 34z via the nozzle 34y.

[0101] The nozzle 34y faces the third internal plate 33a of the third liquid-side member 33, and when viewed from the rear, it does not overlap with the flow diversion opening 33x and does not communicate with the flow diversion opening 33x. The nozzle 34y also faces the fifth internal plate 35a of the fifth liquid-side member 35, which will be described later, and when viewed from the rear, it does not overlap with the second connecting opening 35x, the return flow path 35y, and the supply flow path 35z, and does not communicate with them. The nozzle 34y is located near the center of the fourth internal plate 34a in the left-right direction.

[0102] The rising space 34z is a flow path that extends from the inlet 34e along the longitudinal direction of the liquid header 30 to the upper end side of the liquid header 30 (an example of the first end side). The rising space 34z faces the third internal plate 33a of the third liquid side member 33, and when viewed from the rear, it overlaps with and communicates with the multiple diversion openings 33x.

[0103] The flow path cross-sectional area A of the rising space 34z is formed such that the flow path cross-sectional area A at the first position P1 is different from the flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header 30. The first position P1 is the inlet 34e or the vicinity of the inlet 34e. The flow path cross-sectional area A increases from the first position P1 toward the second position P2. In the outdoor heat exchanger 11, the second position P2 is located at the upper end of the rising space 34z.

[0104] In the outdoor heat exchanger 11, as you move from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A changes as the shape of the flow path cross-section of the rising space 34z changes in a direction perpendicular to the longitudinal direction of the flattened pipe 28 when viewed from the extension direction (vertical direction) of the rising space 34z (in this embodiment, the left-right direction). In other words, in the outdoor heat exchanger 11, as you move from the first position P1 toward the upper end of the liquid header 30, the width of the rising space 34z in the left-right direction changes, causing the flow path cross-sectional area A to change.

[0105] The rising space 34z faces the fifth internal plate 35a of the fifth liquid-side member 35, which will be described later. When viewed from the rear, it does not overlap with the second communication opening 35x, but it overlaps with the return flow path 35y and the supply flow path 35z. The rising space 34z does not communicate with the second communication opening 35x, but it communicates with the return flow path 35y and the supply flow path 35z. The length of the rising space 34z in the longitudinal direction of the liquid header 30 is longer than the length of the introduction space 34x in the longitudinal direction of the liquid header 30, and is longer than the length of the nozzle 34y in the longitudinal direction of the liquid header 30. This makes it possible to increase the number of flattened pipes 28 that communicate via the rising space 34z.

[0106] The rising space 34z is formed by the front surface of the third internal plate 33a of the third liquid-side member 33, the rear surface of the fifth internal plate 35a of the fifth liquid-side member 35 (described later), and the thickness of the left and right edges of the first penetrating portion 34o of the fourth internal plate 34a of the fourth liquid-side member 34. This structure makes it easier to obtain a liquid header 30 that is less prone to errors in the cross-sectional area of ​​the flow path during manufacturing and can stably rise and flow the refrigerant.

[0107] The length (width) of the nozzle 34y in the left-right direction is configured to be shorter than the length of the introduction space 34x in the left-right direction, and also shorter than the minimum length of the rising space 34z in the left-right direction. As a result, when the outdoor heat exchanger 11 is used as a refrigerant evaporator, the refrigerant sent to the introduction space 34x has its flow velocity increased as it passes through the nozzle 34y, promoting its arrival above the rising space 34z. The length of the nozzle 34y in the left-right direction is set to be longer than the thickness of the fourth internal plate 34a. As a result, the size of the opening width relative to the plate thickness can be increased. For example, when the first penetration portion 34o is formed in the fourth internal plate 34a by punching, the load on the punched portion corresponding to the nozzle 34y is reduced, and damage to the punched portion is suppressed. When viewed from the front-rear direction, the branched liquid refrigerant connection pipes 49a to 49e are connected to the center of the introduction space 34x in the left-right direction. When viewed from the front or back, the connection points with the branched liquid refrigerant connection pipes 49a to 49e corresponding to the introduction space 34x, the nozzle 34y, and the rising space 34z are arranged vertically. Therefore, the refrigerant flowing through the branched liquid refrigerant connection pipes 49a to 49e flows into the center of the introduction space 34x in the left-right direction via the external liquid pipe connection opening 37x, the first connecting opening 36x, and the second connecting opening 35x, and can be blown vertically upward from the introduction space 34x towards the rising space 34z via the nozzle 34y without or with little movement in the left-right direction. When viewed from the rear, the multiple diversion openings 33x of the third liquid-side member 33 are all positioned to overlap within the range of a virtual region (the region sandwiched from the left and right by the virtual line VL shown in Figure 14) obtained by virtually extending the nozzle 34y in the longitudinal direction of the liquid header 30. When the outdoor heat exchanger 11 functions as a refrigerant evaporator, the refrigerant that has passed through the nozzle 34y increases in flow velocity and flows upward. However, in the left and right spaces of the rising space 34z slightly above the nozzle 34y, the liquid phase refrigerant tends to stagnate. In contrast, by arranging the multiple diversion openings 33x and the nozzle 34y as described above, it is possible to avoid concentrated flow of liquid phase refrigerant to the diversion opening 33x located at the lowest point of the rising space 34z.

[0108] (4-5) Fifth liquid side member The fifth liquid-side member 35 is a laminated member that is in contact with the front surface of the fourth internal plate 34a of the fourth liquid-side member 34 (the side where the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30). The left-right length of this fifth liquid-side member 35 is the same as the left-right length of the fourth liquid-side member 34. Preferably, the fifth liquid-side member 35 has a cladding layer having a brazing material formed on its surface.

[0109] The fifth liquid-side member 35 includes a fifth internal plate 35a, a second communication opening 35x, a return flow path 35y (an example of a second communication opening), and a supply flow path 35z (an example of a first communication opening).

[0110] The fifth internal plate 35a has a flat plate shape that extends in the vertical and horizontal directions.

[0111] The second connecting opening 35x, the return channel 35y, and the outflow channel 35z are independent openings arranged in order from bottom to top, and all of them penetrate the fifth internal plate 35a in the thickness direction.

[0112] When viewed from the rear, the second communication opening 35x overlaps with the introduction space 34x of the first penetration portion 34o of the fourth liquid-side member 34, and they communicate with each other. Also, when viewed from the rear, the second communication opening 35x overlaps with the first communication opening 36x of the sixth liquid-side member 36, which will be described later, and they communicate with each other. When viewed from the rear, the second communication opening 35x does not overlap with the nozzle 34y or the rising space 34z of the first penetration portion 34o of the fourth liquid-side member 34, and they do not communicate with each other. Also, when viewed from the rear, the second communication opening 35x does not overlap with the descending space 36y of the sixth liquid-side member 36, which will be described later, and they do not communicate with each other.

[0113] When viewed from the rear, the return channel 35y overlaps with the lower end portion of the upward space 34z of the first penetrating portion 34o of the fourth liquid-side member 34 (the end opposite to the outgoing channel 35z), and communicates with the lower end portion of the upward space 34z. Also, when viewed from the rear, the return channel 35y overlaps with the lower end portion of the downward space 36y of the sixth liquid-side member 36, and communicates with the lower end portion of the downward space 36y. However, when viewed from the rear, the return channel 35y does not overlap with the nozzle 34y and does not communicate with the nozzle 34y.

[0114] When viewed from the rear, the supply channel 35z overlaps with the portion near the upper end of the rising space 34z of the first penetrating portion 34o of the fourth liquid-side member 34 (the end opposite to the inlet 34e), and communicates with the portion near the upper end of the rising space 34z. Also, when viewed from the rear, the supply channel 35z overlaps with the portion near the upper end of the descending space 36y of the sixth liquid-side member 36, and communicates with the portion near the upper end of the descending space 36y. In this embodiment, when the liquid header 30 is viewed from the stacking direction of each member, the area of ​​the supply channel 35z is formed to be larger than the area of ​​the return channel 35y. Specifically, in this embodiment, the width of the supply channel 35z in the longitudinal direction of the liquid header 30 is formed to be longer than the width of the return channel 35y in the longitudinal direction of the liquid header 30. This makes it easier for the refrigerant that has risen through the rising space 34z and reached the vicinity of the upper end to pass through the supply channel 35z. Furthermore, in this embodiment, when the liquid header 30 is viewed from the stacking direction of each component, the area of ​​the return channel 35y is formed to be smaller than the area of ​​the supply channel 35z. Specifically, in this embodiment, the width of the return channel 35y in the longitudinal direction of the liquid header 30 is formed to be shorter than the width of the supply channel 35z in the longitudinal direction of the liquid header 30. This suppresses the backflow of refrigerant from the rising space 34z into the return channel 35y.

[0115] (4-6) Sixth liquid side member The sixth liquid-side member 36 is a laminated member that is in contact with the front surface of the fifth internal plate 35a of the fifth liquid-side member 35 (the side where the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30). The length of the sixth liquid-side member 36 is the same as the length of the fifth liquid-side member 35. The sixth liquid-side member 36 does not necessarily have a cladding layer having a brazing material formed on its surface.

[0116] The sixth liquid-side member 36 includes a sixth internal plate 36a, a first communication opening 36x, and a descending space 36y (an example of a second flow path).

[0117] The sixth internal plate 36a has a flat plate shape that extends in the vertical and horizontal directions.

[0118] The first connecting opening 36x and the descending space 36y are independent openings arranged in order from bottom to top, and both are openings that penetrate the sixth internal plate 36a in the thickness direction.

[0119] When viewed from the rear, the first communication opening 36x overlaps with the second communication opening 35x of the fifth liquid-side member 35, and they communicate with each other. Also, when viewed from the rear, the first communication opening 36x overlaps with the external liquid pipe connection opening 37x of the seventh liquid-side member 37, which will be described later, and they communicate with each other.

[0120] The descending space 36y communicates with the supply flow path 35z and is a flow path that extends from the supply flow path 35z along the longitudinal direction of the liquid header 30 to the lower end side of the liquid header 30 (an example of the second end side). When viewed from the rear, the descending space 36y overlaps with a part of the fifth internal plate 35a of the fifth liquid side member 35, the return flow path 35y, and the supply flow path 35z, and communicates with each other. However, when viewed from the rear, the descending space 36y does not overlap with the external liquid pipe connection opening 37x of the seventh liquid side member 37, which will be described later, and they do not communicate with each other.

[0121] In the longitudinal direction of the liquid header 30, the length of the descending space 36y is the same as the length of the ascending space 34z. Therefore, the ascending space 34z and the descending space 36y are connected via the supply flow path 35z near the upper end and via the return flow path 35y near the lower end. Thus, the ascending space 34z, the supply flow path 35z, the descending space 36y, and the return flow path 35y form a loop structure through which the refrigerant circulates. Specifically, the refrigerant flowing from the inlet 34e into the ascending space 34z flows from the supply flow path 35z into the descending space 36y, and then flows back into the ascending space 34z through the return flow path 35y.

[0122] (4-7) 7th liquid side member The seventh liquid-side member 37 is a laminated member that is in contact with the front surface of the sixth internal plate 36a of the sixth liquid-side member 36 (the side where the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30). The length of the seventh liquid-side member 37 is the same as the length of the sixth liquid-side member 36. Preferably, the seventh liquid-side member 37 has a cladding layer having a brazing material formed on its surface.

[0123] The seventh liquid-side member 37 has a liquid-side outer plate 37a and an outer liquid pipe connection opening 37x.

[0124] The liquid-side outer plate 37a has a flat plate shape that extends in the vertical and horizontal directions.

[0125] The external liquid pipe connection opening 37x is an opening that penetrates the liquid-side external plate 37a in the thickness direction. When viewed from the rear, the external liquid pipe connection opening 37x overlaps with a portion of the first communication opening 36x of the sixth liquid-side member 36 and communicates with it. However, when viewed from the rear, the external liquid pipe connection opening 37x does not overlap with the lowering space 36y of the sixth liquid-side member 36 and does not communicate with it.

[0126] The external liquid pipe connection opening 37x is a circular opening into which one of the branch liquid refrigerant connection pipes 49a to 49e is inserted and connected. As a result, when the outdoor heat exchanger 11 functions as a refrigerant evaporator, the refrigerant flowing through each branch liquid refrigerant connection pipe 49a to 49e is sent to the introduction space 34x of the first penetration portion 34o via the first communication opening 36x and the second communication opening 35x.

[0127] Furthermore, the front surface of the seventh liquid-side member 37 is in contact with and crimped to the first liquid-side claw portion 31d and the second liquid-side claw portion 31e of the first liquid-side member 31.

[0128] (4-8) Regarding the repetition of shapes in subspaces In the above explanation, we focus on one of the sub-spaces 23a to 23e, which constitute the liquid-side internal space 23 of the liquid header 30, to which one of the branched liquid refrigerant connection pipes 49a to 49e is connected.

[0129] Therefore, for example, in the seventh liquid-side member 37, each external liquid pipe connection opening 37x corresponding to each branch liquid refrigerant connection pipe 49a to 49e is formed on a single liquid-side outer plate 37a, aligned in the longitudinal direction of the liquid header 30. Similarly, in the fourth liquid-side member 34, a first through-port 34o including an introduction space 34x, a nozzle 34y, and an upward space 34z is formed on a single fourth inner plate 34a, aligned in the longitudinal direction of the liquid header 30.

[0130] (5) Refrigerant flow in the liquid header The following describes the flow of refrigerant in the liquid header 30 when the outdoor heat exchanger 11 functions as a refrigerant evaporator. Note that when the outdoor heat exchanger 11 functions as a refrigerant condenser or radiator, the direction of refrigerant flow is opposite to that when it functions as an evaporator.

[0131] First, the liquid-phase refrigerant or gas-liquid two-phase refrigerant that has been divided and flowed through multiple diversion pipes 22a to 22e in the diversion device 22 flows through branch liquid refrigerant connection pipes 49a to 49e, passes through the external liquid pipe connection opening 37x formed in the liquid-side outer plate 37a of the seventh liquid-side member 37, and flows into each sub-space 23a to 23e of the liquid header 30. Specifically, the refrigerant flows into the first communication opening 36x in each sub-space 23a to 23e.

[0132] The refrigerant that flows into the first connecting opening 36x flows through the second connecting opening 35x into the introduction space 34x of the first penetrating portion 34o of the fourth liquid-side member 34.

[0133] The refrigerant flowing into the introduction space 34x has its flow velocity increased as it passes through the nozzle 34y, and then flows into the rising space 34z from the inlet 34e. The refrigerant flowing into the rising space 34z splits and flows toward each diversion opening 33x, heading toward the vicinity of the upper end of the rising space 34z. The refrigerant that reaches the vicinity of the upper end of the rising space 34z flows into the descending space 36y via the outflow channel 35z.

[0134] The refrigerant that flows into the descending space 36y descends and is returned again to the space above the nozzle 34y, near the lower part of the ascending space 34z, via the return channel 35y. Here, in the ascending space 34z, the flow velocity of the refrigerant increases as it passes through the nozzle 34y, so the static pressure in the portion of the ascending space 34z near the return channel 35y is lower than that in the portion of the descending space 36y near the return channel 35y. For this reason, the refrigerant that descends in the descending space 36y is more easily returned to the ascending space 34z via the return channel 35y.

[0135] In this way, the refrigerant can be circulated in a loop by the rising space 34z, the supply flow path 35z, the descending space 36y, and the return flow path 35y. Therefore, even if some refrigerant does not flow through any of the branching openings 33x when it flows upward in the rising space 34z, it can be returned to the rising space 34z via the supply flow path 35z, the descending space 36y, and the return flow path 35y, making it easier for it to flow through any of the branching openings 33x. Furthermore, even when a gas-liquid two-phase refrigerant flows in, mixing of the liquid phase refrigerant and the gas phase refrigerant is promoted.

[0136] As described above, the refrigerant that has been diverted and flowed through the diversion opening 33x flows into each flattened pipe 28 through the insertion space 32s while maintaining its diverged state.

[0137] (6) Features of the Embodiment (6-1) The outdoor heat exchanger 11 comprises a plurality of flattened tubes 28 and a cylindrical liquid header 30. The liquid header 30 has subspaces 23a to 23e formed inside, which are connected to the plurality of flattened tubes 28. The subspaces 23a to 23e have an upward space 34z, a supply flow path 35z, and a downward space 36y. The upward space 34z extends from the inlet 34e into which the refrigerant flows in, along the longitudinal direction of the liquid header 30, toward the upper end of the liquid header 30. The supply flow path 35z communicates with the end of the upward space 34z opposite to the inlet 34e. The downward space 36y communicates with the supply flow path 35z and extends from the supply flow path 35z along the longitudinal direction of the liquid header 30 toward the lower end of the liquid header 30. The plurality of flattened tubes 28 are connected to the upward space 34z so as to intersect the longitudinal direction of the liquid header 30. The upward space 34z has a different flow path cross-sectional area A at the first position P1 and a different flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 towards the upper end of the liquid header 30.

[0138] When the air conditioning system 1 performs heating operation and the outdoor heat exchanger 11 functions as a refrigerant evaporator, the gas-liquid two-phase refrigerant that has reached the diverter 22 from the liquid refrigerant pipe 20 flows through the diverter pipes 22a to 22e into the sub-spaces 23a to 23e that constitute the liquid-side internal space 23 of the liquid header 30. At this time, if an imbalance in the pressure distribution of the gas-liquid two-phase refrigerant flowing into each sub-space 23a to 23e occurs, a flow bias may occur in the multiple flat pipes 28 connected to each sub-space 23a to 23e, resulting in an uneven distribution of liquid-phase and gas-phase refrigerant.

[0139] In the outdoor heat exchanger 11, the flow path cross-sectional area A is made different at the first position P1 and the second position P2 of the rising space 34z to resolve this issue and suppress the occurrence of uneven flow in the flattened pipe 28. Specifically, in the rising space (not shown) where the flow path cross-sectional area A is formed to be constant from the inlet 34e to the upper end, a location where the distribution of liquid phase refrigerant is reduced is found, and the flow path cross-sectional area A at that location is made larger than that of other parts. As a result, the imbalance in the pressure distribution of the refrigerant in the rising space 34z is resolved, and the occurrence of uneven flow in the flattened pipe 28 is suppressed.

[0140] (6-2) The first location P1 is near the inlet.

[0141] (6-3) The descending space 36y has a return channel 35y that communicates with the ascending space 34z at the end opposite to the supply channel 35z. The refrigerant that flows into the ascending space 34z from the inlet 34e flows into the descending space 36y from the supply channel 35z, and then flows into the ascending space 34z through the return channel 35y.

[0142] The outdoor heat exchanger 11 circulates the refrigerant through an upward space 34z, a supply flow path 35z, a downward space 36y, and a return flow path 35y, thereby promoting the mixing of liquid-phase refrigerant and gaseous-phase refrigerant and eliminating the pressure distribution imbalance in the upward space 34z.

[0143] (6-4) The flow path cross-sectional area A increases as you move from the first position P1 to the second position P2.

[0144] The flow deviation in the flattened pipe 28 described above varies depending on the degree of dryness of the refrigerant in the liquid header 30 and the magnitude of the refrigerant circulation rate. Specifically, in the rising space 34z where the flow path cross-sectional area A is constant from the inlet 34e to the upper end, if the degree of dryness of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 (the joint between the sub-spaces 23a to 23e and the branched liquid refrigerant connecting pipes 49a to 49e) is greater than 0.25, and the average flow velocity Vm of the refrigerant in the rising space 34z is 2 m / sec or less, then the amount of gaseous refrigerant tends to increase as you go higher up the rising space 34z. As a result, a large amount of gaseous refrigerant tends to flow into the flattened pipe 28 located above the group of flattened pipes 28G.

[0145] In the outdoor heat exchanger 11, an upward space 34z is formed such that the flow path cross-sectional area A increases as it moves from the first position P1 to the second position P2. As a result, the refrigerant flowing in from the inlet 34e is promoted to move upward in the upward space 34z. Consequently, the outdoor heat exchanger 11 moves the liquid phase refrigerant flowing in from the inlet 34e, along with the gaseous phase refrigerant, upward in the upward space 34z, thereby eliminating the imbalance in the pressure distribution in the upward space 34z.

[0146] The average flow velocity Vm of the refrigerant can be calculated using the following equation 1. TIFF2026053614000025.tif47162

[0147] The refrigerant circulation rate Gr can be determined by known methods using the rotational speed of the compressor 8, the pressure and temperature of the refrigerant drawn in by the compressor 8, the pressure of the refrigerant flowing on the discharge side of the compressor 8, and the displacement and efficiency of the piston in the compressor 8.

[0148] Furthermore, the average density ρm of the refrigerant can be calculated using the following equation 2. TIFF2026053614000026.tif47162

[0149] (6-5) The cross-sectional shape of the flow path in the upward space 34z changes in a direction perpendicular to the longitudinal direction of the flattened pipe 28 as you move from the first position P1 toward the upper end of the liquid header 30.

[0150] (6-6) The liquid header 30 has its longitudinal direction aligned with the vertical direction.

[0151] (6-7) The air conditioning unit 1 operates in such a way that the dryness of the refrigerant at the inlet of the outdoor heat exchanger 11 is 0.25 or higher.

[0152] As described above, when the dryness of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 is 0.25 or higher, an imbalance in the pressure distribution in the rising space 34z is likely to occur. For this reason, the outdoor heat exchanger 11 can effectively suppress the occurrence of uneven flow in the flattened pipe 28 in an air conditioning system 1 that operates in a manner in which the dryness of the refrigerant is 0.25 or higher.

[0153] An operation in which the dryness of the refrigerant is 0.25 or higher is, for example, an operation in which a two-phase transport is performed in which the refrigerant in a gas-liquid two-phase state is flowed through the liquid refrigerant connecting pipe 4 and sent from the outdoor unit 2 to the indoor unit 9.

[0154] (6-8) The refrigerant circuit 6 is filled with a single refrigerant consisting of propane, CO2, and isobutane, or a mixed refrigerant containing propane, CO2, and isobutane.

[0155] In refrigerant circuits filled with natural refrigerants such as propane, CO2, and isobutane, the degree of dryness at the heat exchanger inlet tends to be high. However, by employing an outdoor heat exchanger 11, the occurrence of flow deviation in the flattened tube 28 is suppressed even when using natural refrigerants such as propane, CO2, and isobutane.

[0156] (7) Variant (7-1) Variation 1A The mode in which the flow path cross-sectional area A is changed as one moves from the first position P1 toward the upper end of the liquid header 30 is not limited to the mode described above. As one moves from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A may be changed as the flow path cross-sectional shape of the rising space 34z changes in the longitudinal direction of the flattened pipe 28 as viewed from the extension direction of the rising space 34z. In other words, as one moves from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A may be changed as the width of the rising space 34z in the front-rear direction changes.

[0157] Specifically, for example, the surface of the third internal plate 33a facing the rising space 34z may be formed to be recessed towards the rear as it moves from the first position P1 toward the upper end of the liquid header 30. Similarly, the surface of the fifth internal plate 35a facing the rising space 34z may be formed to be recessed towards the front as it moves from the first position P1 toward the upper end of the liquid header 30. Figure 18 is a cross-sectional view of the area around the rising space 34z of the outdoor heat exchanger 11 according to Modification 1A, viewed from the right side. In the liquid header 30 of the outdoor heat exchanger 11 according to Modification 1A shown in Figure 18, recesses are formed in both the third internal plate 33a and the fifth internal plate 35a.

[0158] (7-2) Modification 1B In the outdoor heat exchanger 11, the liquid header 30 forms a plurality of sub-spaces 23a to 23e, which are refrigerant flow paths, by first liquid-side member 31, second liquid-side member 32, third liquid-side member 33, fourth liquid-side member 34, fifth liquid-side member 35, sixth liquid-side member 36, and seventh liquid-side member 37. However, the plurality of sub-spaces 23a to 23e may be formed by combining, for example, a plurality of tubular members.

[0159] Therefore, the rising space 34z may also be formed by a tubular member in which the flow path cross-sectional area A at the first position P1 and the flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header 30, are different.

[0160] <Second Embodiment> The outdoor heat exchanger (not shown) according to the second embodiment of this disclosure will be described, focusing on the differences from the first embodiment. The difference between the outdoor heat exchanger according to the second embodiment and the outdoor heat exchanger 11 is the shape of the rising space 34z1 formed in the fourth liquid-side member 38 of the liquid header 30. In the following, features that are the same as or corresponding to the first embodiment will be denoted by the same reference numerals and their description will be omitted.

[0161] (1) Rising space of the fourth liquid-side member Figure 19 is an exploded perspective view of the portion near the upper end of the liquid header 30 of the outdoor heat exchanger according to the second embodiment. Figure 20 is a schematic view of the fourth liquid-side member 38 of the liquid header 30 of the outdoor heat exchanger according to the second embodiment, viewed from the rear.

[0162] The rising space 34z1 is formed at the connection point with the nozzle 34y where an inlet 34e is formed, into which refrigerant that has passed through the nozzle 34y flows when the outdoor heat exchanger 11 functions as a refrigerant evaporator. The rising space 34z1 is a flow path that extends from the inlet 34e along the longitudinal direction of the liquid header 30 to the upper end of the liquid header 30. The rising space 34z1 faces the third internal plate 33a of the third liquid-side member 33, overlaps with and communicates with a plurality of diversion openings 33x when viewed from the rear.

[0163] The flow path cross-sectional area A of the rising space 34z1 is formed such that the flow path cross-sectional area A at the first position P1 is different from the flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header 30. The first position P1 is the inlet 34e or the vicinity of the inlet 34e. The flow path cross-sectional area A increases from the first position P1 toward the second position P2. In the outdoor heat exchanger according to the second embodiment, the second position P2 is located approximately in the center of the rising space 34z1 in the longitudinal direction of the liquid header 30. Furthermore, the flow path cross-sectional area A of the rising space 34z1 decreases from the second position P2 toward the upper end of the liquid header 30, and becomes the same as the flow path cross-sectional area A at the upper end of the liquid header 30 as at the first position P1.

[0164] In the outdoor heat exchanger according to the second embodiment, as you move from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A changes as the cross-sectional shape of the flow path of the rising space 34z1 changes in a direction perpendicular to the longitudinal direction of the flattened pipe 28 when viewed from the extension direction (vertical direction) of the rising space 34z1 (in this embodiment, the left-right direction). In other words, in the outdoor heat exchanger according to the second embodiment, as you move from the first position P1 toward the upper end of the liquid header 30, the width of the rising space 34z1 in the left-right direction changes as the cross-sectional area A of the flow path changes.

[0165] (2) Characteristics In the outdoor heat exchanger according to the second embodiment, the rising space 34z1 has a second position P2 located in the center of the longitudinal direction of the liquid header 30. The flow path cross-sectional area A decreases as it moves from the second position P2 toward the upper end of the liquid header 30.

[0166] In the rising space 34z, where the flow path cross-sectional area A is constant from the inlet 34e to the upper end, if the dryness of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 is greater than 0.25 and the average flow velocity Vm of the refrigerant in the rising space 34z is greater than 2 m / sec, then the amount of gaseous refrigerant tends to increase towards the center of the rising space 34z. As a result, a large amount of gaseous refrigerant tends to flow into the flat tube 28 located in the center of the flat tube group 28G in the vertical direction.

[0167] In the outdoor heat exchanger according to the second embodiment, the second position P2 is located approximately in the center of the rising space 34z1 in the longitudinal direction of the liquid header 30. Furthermore, the flow path cross-sectional area A is formed to increase from the first position P1 toward the second position P2, and then decrease from the second position P2 toward the upper end of the liquid header 30. As a result, the refrigerant flowing in from the inlet 34e is promoted to move toward the center of the rising space 34z in the vertical direction. Consequently, the outdoor heat exchanger according to the second embodiment moves the liquid phase refrigerant flowing in from the inlet 34e together with the gas phase refrigerant toward the center of the rising space 34z, thereby eliminating the imbalance in the pressure distribution in the rising space 34z.

[0168] (3) Modification 2A The mode of increasing the flow path cross-sectional area A as one moves from the first position P1 to the second position P2 is not limited to the mode described above. As one moves from the first position P1 towards the upper end of the liquid header 30, the flow path cross-sectional area A may change as the flow path cross-sectional shape of the rising space 34z changes in the longitudinal direction of the flattened pipe 28 as viewed from the extending direction of the rising space 34z1. In other words, as one moves from the first position P1 towards the upper end of the liquid header 30, the flow path cross-sectional area A may increase as the width of the rising space 34z1 in the front-rear direction increases.

[0169] Specifically, for example, the surface of the third internal plate 33a facing the rising space 34z1 may be formed to be recessed towards the rear as it moves from the first position P1 and the upper end of the liquid header 30 toward the second position P2. Similarly, the surface of the fifth internal plate 35a facing the rising space 34z1 may be formed to be recessed towards the front as it moves from the first position P1 and the upper end of the liquid header 30 toward the second position P2. Figure 21 is a cross-sectional view of the area around the rising space 34z1 of the outdoor heat exchanger according to modified example 2A, viewed from the right side. In the liquid header 30 of the outdoor heat exchanger according to modified example 2A shown in Figure 21, recesses are formed in both the third internal plate 33a and the fifth internal plate 35a.

[0170] While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Explanation of symbols]

[0171] 1. Air conditioning system 11 Outdoor heat exchanger (heat exchanger) 23 Liquid-side internal space 23a~23e Subspace (refrigerant flow path) 28 Flattened tubes (heat transfer tubes) 30 Liquid Header (Header) 34e Inlet 34z ascending space (first channel) 35y Return channel (2nd communication port) 35z Outgoing flow path (1st communication port) 36y Descending space (second channel) A Flow channel cross-sectional area P1 1st position P2 2nd position [Prior art documents] [Patent Documents]

[0172] [Patent Document 1] Japanese Patent Publication No. 2016-125748

Claims

1. Multiple heat transfer tubes (28), A cylindrical header (30) has refrigerant flow paths (23a to 23e) connected to a plurality of heat transfer tubes formed inside, and A heat exchanger equipped with, The refrigerant flow path is A first flow path (34z) extends from the inlet (34e) into which the refrigerant flows in, along the first direction which is the longitudinal direction of the header, toward the first end of the header, A first communication port (35z) that communicates with the end of the first flow path opposite to the inlet, A second flow path (36y) communicates with the first communication port and extends from the first communication port toward the second end of the header along the first direction. It has, Multiple heat transfer tubes are, Connected to the first flow path so as to intersect the first direction, The first channel is, The flow path cross-sectional area (A) at the first position (P1) is different from the flow path cross-sectional area at the second position (P2), which is a predetermined distance from the first position toward the first end of the header. heat exchanger.

2. The first position is, Near the aforementioned inlet, The heat exchanger according to claim 1.

3. The refrigerant flow path is The second flow path further has a second communication port (35y) that communicates with the first flow path at the end opposite to the first communication port, The refrigerant that flows into the first flow path from the inlet is After flowing into the second channel from the first communication port, it flows into the first channel through the second communication port. A heat exchanger according to claim 1 or 2.

4. The cross-sectional area of ​​the aforementioned channel is It increases as you move from the first position to the second position. A heat exchanger according to any one of claims 1 to 3.

5. The second position is, Located in the center in the first direction, The cross-sectional area of ​​the aforementioned channel is The distance decreases from the second position toward the first end of the header. The heat exchanger according to claim 4.

6. The cross-sectional view of the first channel is As you move from the first position toward the first end of the header, the shape changes in a direction perpendicular to the longitudinal direction of the heat transfer tube as viewed from the extending direction of the first flow path. The heat exchanger according to claim 4 or 5.

7. The cross-sectional view of the first channel is As you move from the first position toward the first end of the header, the shape of the heat transfer tube changes in the longitudinal direction as viewed from the extending direction of the first flow path. A heat exchanger according to any one of claims 4 to 6.

8. The aforementioned header is, The longitudinal direction coincides with the vertical direction. A heat exchanger according to any one of claims 1 to 7.

9. A refrigerant circuit comprising a heat exchanger according to any one of claims 1 to 8, The operation is performed such that the dryness of the refrigerant at the inlet of the heat exchanger is 0.25 or higher. Air conditioning system.

10. A refrigerant circuit comprising a heat exchanger according to any one of claims 1 to 8, The aforementioned refrigerant circuit is Propane, CO ２ A single refrigerant consisting of either , or isobutane, or propane, CO2 ２ A mixed refrigerant containing either isobutane is filled in Air conditioning system.

Images